In the description that follows references are made to certain compounds, devices and methods. These references should not necessarily be construed as an admission that such compounds, devices and methods qualify as prior art under the applicable statutory provisions.
The term “nano-structured” or “nanostructure” material is used by those familiar with the art to designate materials including nanoparticles with a particle size or less than 100 nm, nanotubes (e.g.—carbon nanotubes), non-carbon nanotubes, nanorods or nanowires (e.g.—Si nanowires with a diameter of approximately 1-100 nm). These types of materials have been shown to exhibit certain properties that have raised interest in a variety of applications.
U.S. Pat. No. 6,280,697 entitled “Nanotube-Based High Energy Material and Method”, the disclosure of which is incorporated herein by reference, in its entirety, discloses the fabrication of carbon-based nanotube materials and their use as a battery electrode material.
U.S. Pat. No. 6,277,318 entitled “Method for Fabrication of Patterned Carbon Nanotube Films”, the disclosure of which is incorporated herein by reference, in its entirety, discloses a method of fabricating adherent, patterned carbon nanotube films onto a substrate.
U.S. Patent No. 6,334,939 entitled “Nanoscructure-Based High Energy Material and Method”, the disclosure of which is incorporated herein by reference, in its entirety, discloses a nanostructure material having an intercalated alkali metal. Such materials are described as being useful in certain battery applications.
(Ser. No. 09/351,537 entitled “Device Comprising Thin Film Carbon Nanotube Electron Field Emitter Structure”) the disclosure of which is incorporated herein by reference, in its entirety, discloses a carbon nanotube-based electron emitter structure.
Gas discharge tubes are devices that typically comprise parallel electrodes in a sealed vacuum chamber containing a noble gas, or mixture of noble gases, at a particular pressure. Gas tubes are designed to be insulators under normal voltage and current conditions. However, under large transient voltages, such as from lightning, a discharge is formed between the electrodes, causing a plasma breakdown of the noble gas(es) inside the chamber. In the plasma state, the gas tube becomes a conductor, which is designed to shunt or short circuit the system in which it is incorporated, thereby protecting other components of the system from damage caused by the over voltage.
Gas discharge tubes are robust, moderately expensive, and have a relatively small shunt capacitance, so bandwidth of high-frequency circuits is not limited as much as by other solid state protectors. Moreover, gas discharge tubes can carry much higher currents than solid state protectors.
However, conventional gas discharge tubes posses certain disadvantages. Gas discharge tubes are unreliable in term of the “mean turn-on voltage”, that is the voltage required to turn the device into a conductor can vary significantly from run to run (i.e.—repeated exposures to overvoltages).
Moreover, since a relatively high electric field is required to cause the plasma breakdown, the electrodes are typically provided with a very small separation distance. Small variations in the gap spacing can cause large variability in the breakdown voltage. Thus, manufacture of such devices must be carried out with great precision in order to avoid such variances.
Thus, it would be advantageous to provide an improved device which exhibits smaller variances in mean turn-on voltage, and can produce a high electric field with less dependence upon a precise, small electrode separation distance.